The last 20 years have seen an upheaval in castle studies. Traditionally, castles have been seen as primarily military structures, and their development interpreted in terms of attack and defence. More recently, scholars have developed an alternative view, stressing the castle’s social and symbolic role. ‘Debate’ between these views has often been quite heated, reverting to an either/or view that is unhelpful. In this talk, I focus neither on defence nor on symbolism, but on how castles work. Castles are a place of work, and they do work in different ways – they control the flow of things, of animals and of humans around the landscape. This new view of castles, then, is focused on practice and political economy. I give examples from my own research on castles in south-east England, particularly Bodiam, to illustrate my points.